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chemical compounds made by elimination of water from other compounds; inorganic examples are calcium oxide, derived from calcium hydroxide, and sulfur trioxide, derived from sulfuric acid; organic anhydrides used industrially to make other compounds—mixed with water to make carboxylic acids, with alcohols to obtain esters, and with ammonia to obtain amides; acetic anhydride used in manufacture of aspirin, magnetic tape, and fibers.

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